Wide ratio transmissions with three interconnected planetary gear sets and a stationary member

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms, one fixed interconnection and one grounded planetary gear member. The powertrain includes an engine and torque converter that is continuously connected to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members and the transmission housing, and are operated in combinations of two to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No.6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397issued to Raghavan, Bucknor and Usoro. Eight speed transmissions aredisclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Hakatransmission utilizes three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. The Hakatransmission requires two double-transition shifts. Seven-, eight- andnine-speed transmissions provide further improvements in accelerationand fuel economy over six-speed transmissions. However, like thesix-speed transmissions discussed above, the development of seven-,eight- and nine-speed transmissions has been precluded because ofcomplexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.). Additionally, the first, second or third members of eachgear set may be counted “first” to “third” in any order in the drawings(i.e., top to bottom, bottom to top, etc.) for each gear set.

In another aspect of the present invention, planet carrier assemblymembers of each of the planetary gear sets may be single pinion-carriersor double pinion-carriers.

In yet another aspect of the present invention, a first member of thefirst planetary gear set is continuously interconnected with a firstmember of the second planetary gear set and with a first member of thethird planetary gear set through a first interconnecting member.

In yet another aspect of the present invention, a second member of thefirst planetary gear set is continuously interconnected with astationary member (transmission housing).

In yet a further aspect of the invention, each family memberincorporates an input shaft which is continuously connected with amember of the planetary gear sets and an output shaft which iscontinuously connected with another member of the planetary gear sets.

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst planetary gear set with a member of the second or third planetarygear set.

In another aspect of the invention, a second torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thesecond planetary gear set with a member of the third planetary gear set.

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thethird planetary gear set with a member of the first or second planetarygear set.

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set.

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or third planetary gear set with another member of the first,second or third planetary gear set. Alternatively, the fifthtorque-transmitting mechanism, such as a brake, selectivelyinterconnects a member of the first or third planetary gear set with thestationary member (transmission housing).

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thesecond or third planetary gear set with another member of the first,second or third planetary gear set. Alternatively, the sixthtorque-transmitting mechanism such as a brake, selectively interconnectsa member of the second or third planetary gear set with the stationarymember (transmission housing).

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectivelyinterconnects a member of the first, second or third planetary gear setwith the stationary member (transmission housing).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of two to yield atleast eight forward speed ratios and at least one reverse speed ratio.

The resulting transmission provides a significantly wider ratio spreadin comparison to transmissions with fewer speed ratios.

The above features and other features and advantages of the presentinvention are readily apparent from the following detailed descriptionof the best modes for carrying out the invention when taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a;

FIG. 11 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 11 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11 a.

FIG. 12 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 12 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 12 a;

FIG. 13 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 13 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 13 a;

FIG. 14 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 14 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 14 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine and torque converter12, a planetary transmission 14, and a conventional final drivemechanism 16.

The planetary transmission 14 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 18, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 18 includesthree planetary gear sets 20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47 rotatablymounted on a carrier member 49 and disposed in meshing relationship withboth the sun gear member 42 and the ring gear member 44.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54 and 56 are rotating-type torque-transmittingmechanisms, commonly termed clutches. The torque-transmitting mechanisms57, 58 and 59 are stationary-type torque-transmitting mechanisms,commonly termed brakes or reaction clutches.

The input shaft 17 is continuously connected with the sun gear member32, and the output shaft 19 is continuously connected with the ring gearmember 44. The planet carrier assembly member 26 is continuouslyconnected with the ring gear member 34 and with the sun gear member 42through the interconnecting member 70. The interconnecting member 70 maybe one component or separate components. The sun gear member 22 iscontinuously connected with the transmission housing 60 through theinterconnecting member 72.

The ring gear member 24 is selectively connectable with the sun gearmember 32 through the clutch 50. The ring gear member 24 is selectivelyconnectable with the planet carrier assembly member 36 through theclutch 52. The sun gear member 32 is selectively connectable with theplanet carrier assembly member 46 through the clutch 54. The planetcarrier assembly member 36 is selectively connectable with the planetcarrier assembly member 46 through the clutch 56. The ring gear member24 is selectively connectable with the transmission housing 60 throughthe brake 57. The planet carrier assembly member 26 is selectivelyconnectable with the transmission housing 60 through the brake 58. Theplanet carrier assembly member 46 is selectively connectable with thetransmission housing 60 through the brake 59.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of two to provide eight forward speed ratios and tworeverse speed ratios.

The second reverse (Reverse 2) speed ratio is established with theengagement of the clutch 52 and the brake 59. The clutch 52 connects thering gear member 24 with the planet carrier assembly member 36, and thebrake 59 connects the planet carrier assembly member 46 with thetransmission housing 60. The ring gear member 24 rotates at the samespeed as the planet carrier assembly member 36. The planet carrierassembly member 26 rotates at the same speed as the ring gear member 34and the sun gear member 42. The sun gear member 22 does not rotate. Thering gear member 24 rotates at a speed determined from the speed of theplanet carrier assembly member 26 and the ring gear/sun gear tooth ratioof the planetary gear set 20. The sun gear member 32 rotates at the samespeed as the input shaft 17. The ring gear member 34 rotates at a speeddetermined from the speed of the planet carrier assembly member 36, thespeed of the sun gear member 32 and the ring gear/sun gear tooth ratioof the planetary gear set 30. The planet carrier assembly member 46 doesnot rotate. The ring gear member 44 rotates at the same speed as theoutput shaft 19. The ring gear member 44, and therefore the output shaft19, rotates at a speed determined from the speed of the sun gear member42 and the ring gear/sun gear tooth ratio of the planetary gear set 40.The numerical value of the second reverse (Reverse 2) speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30 and 40.

The first reverse (Reverse 1) speed ratio is established with theengagement of the clutch 50 and the brake 59. The clutch 50 connects thering gear member 24 with the sun gear member 32, and the brake 59connects the planet carrier assembly member 46 with the transmissionhousing 60. The ring gear member 24 and the sun gear member 32 rotate atthe same speed as the input shaft 17. The planet carrier assembly member26 and the ring gear member 34 rotate at the same speed as the sun gearmember 42. The sun gear member 22 does not rotate. The ring gear member24 rotates at a speed determined from the speed of the planet carrierassembly member 26 and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The planet carrier assembly member 46 does notrotate. The ring gear member 44 rotates at the same speed as the outputshaft 19. The ring gear member 44, and therefore the output shaft 19,rotates at a speed determined from the speed of the sun gear member 42and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the first reverse (Reverse 1) speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20 and 40.

The first forward speed ratio is established with the engagement of theclutch 56 and the brake 59. The clutch 56 connects the planet carrierassembly member 36 with the planet carrier assembly member 46, and thebrake 59 connects the planet carrier assembly member 46 with thetransmission housing 60. The sun gear member 32 rotates at the samespeed as the input shaft 17. The planet carrier assembly member 36 andthe planet carrier assembly member 46 do not rotate. The ring gearmember 34 and the planet carrier assembly member 26 rotate at the samespeed as the sun gear member 42. The ring gear member 34 rotates at aspeed determined from the speed of the sun gear member 32 and the ringgear/sun gear tooth ratio of the planetary gear set 30. The ring gearmember 44 rotates at the same speed as the output shaft 19. The ringgear member 44, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the sun gear member 42 and the ringgear/sun gear tooth ratio of the planetary gear set 40. The numericalvalue of the first forward speed ratio is determined utilizing the ringgear/sun gear tooth ratios of the planetary gear sets 30 and 40.

The second forward speed ratio is established with the engagement of theclutch 56 and the brake 57. The clutch 56 connects the planet carrierassembly member 36 with the planet carrier assembly member 46, and thebrake 57 connects the ring gear member 24 with the transmission housing60. The sun gear member 32 rotates at the same speed as the input shaft17. The ring gear member 34, the planetary gear set 20 and the sun gearmember 42 do not rotate. The planet carrier assembly member 36 rotatesat the same speed as the planet carrier assembly member 46. The speed ofthe ring gear member 34 is determined from the speed of the planetcarrier assembly member 36, the speed of the sun gear member 32 and thering gear/sun gear tooth ratio of the planetary gear set 30. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member 46and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets30 and 40.

The third forward speed ratio is established with the engagement of theclutch 52 and the clutch 56. The clutch 52 connects the ring gear member24 with the planet carrier assembly member 36, and the clutch 56connects the planet carrier assembly member 36 with the planet carrierassembly member 46. The ring gear member 24 and the planet carrierassembly member 36 rotate at the same speed as the planet carrierassembly member 46. The planet carrier assembly member 26 and the ringgear member 34 rotate at the same speed as the sun gear member 42. Thesun gear member 22 does not rotate. The ring gear member 24 rotates at aspeed determined from the speed of the planet carrier assembly member 26and the ring gear/sun gear tooth ratio of the planetary gear set 20. Thesun gear member 32 rotates at the same speed as the input shaft 17. Thespeed of the ring gear member 34 is determined from the speed of theplanet carrier assembly member 36, the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thering gear member 44 rotates at the same speed as the output shaft 19.The ring gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42 and the ring gear/sun gear toothratio of the planetary gear set 40. The numerical value of the thirdforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 20, 30 and 40.

The fourth forward speed ratio is established with the engagement of theclutch 50 and the clutch 56. The clutch 50 connects the ring gear member24 with the sun gear member 32, and the clutch 56 connects the planetcarrier assembly member 36 with the planet carrier assembly member 46.The ring gear member 24 and the sun gear member 32 rotate at the samespeed as the input shaft 17. The planet carrier assembly member 26 andthe ring gear member 34 rotate at the same speed as the sun gear member42. The sun gear member 22 does not rotate. The speed of the ring gearmember 24 is determined from the speed of the planet carrier assemblymember 26 and the ring gear/sun gear tooth ratio of the planetary gearset 20. The planet carrier assembly member 36 rotates at the same speedas the planet carrier assembly member 46. The speed of the ring gearmember 34 is determined from the speed of the planet carrier assemblymember 36, the speed of the sun gear member 32 and the ring gear/sungear tooth ratio of the planetary gear set 30. The ring gear member 44rotates at the same speed as the output shaft 19. The ring gear member44, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the planet carrier assembly member 46, the speed ofthe sun gear member 42 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The numerical value of the fourth forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30 and 40.

The fifth forward speed ratio is established with the engagement of theclutches 54 and 56. In this configuration, the input shaft 17 isdirectly connected with the output shaft 19. The numerical value of thefifth forward speed ratio is 1.

The sixth forward speed ratio is established with the engagement of theclutch 50 and the clutch 54. The clutch 50 connects the ring gear member24 with the sun gear member 32, and the clutch 54 connects the sun gearmember 32 with the planet carrier assembly member 46. The ring gearmember 24, the sun gear member 32 and the planet carrier assembly member46 rotate at the same speed as the input shaft 17. The planet carrierassembly member 26 and the ring gear member 34 rotate at the same speedas the sun gear member 42. The sun gear member 22 does not rotate. Thering gear member 24 rotates at a speed determined from the speed of theplanet carrier assembly member 26 and the ring gear/sun gear tooth ratioof the planetary gear set 20. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46, the speed of the sungear member 42 and the ring gear/sun gear tooth ratio of the planetarygear set 40. The numerical value of the sixth forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20 and 40.

The seventh forward speed ratio is established with the engagement ofthe clutch 52 and the clutch 54. The clutch 52 connects the ring gearmember 24 with the planet carrier assembly member 36, and the clutch 54connects the sun gear member 32 with the planet carrier assembly member46. The ring gear member 24 rotates at the same speed as the planetcarrier assembly member 36. The planet carrier assembly member 26 andthe ring gear member 34 rotate at the same speed as the sun gear member42. The sun gear member 22 does not rotate. The ring gear member 24rotates at a speed determined from the speed of the planet carrierassembly member 26 and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The sun gear member 32 and the planetary gear set46 rotate at the same speed as the input shaft 17. The planet carrierassembly member 36 rotates at the same speed as the ring gear member 24.The ring gear member 34 and the planet carrier assembly member 26 rotateat the same speed as the sun gear member 42. The speed of the ring gearmember 34 is determined from the speed of the planet carrier assemblymember 36, the speed of the sun gear member 32 and the ring gear/sungear tooth ratio of the planetary gear set 30. The ring gear member 44rotates at the same speed as the output shaft 19. The ring gear member44, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the planet carrier assembly member 46, the speed ofthe sun gear member 42 and the ring gear/sun gear tooth ratio of theplanetary gear set 40. The numerical value of the seventh forward speedratio is determined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20, 30 and 40.

The eighth forward speed ratio is established with the engagement of theclutch 54 and the brake 58. The clutch 54 connects the sun gear member32 with the planet carrier assembly member 46, and the brake 58 connectsthe planet carrier assembly member 26 with the transmission housing 60.The planet carrier assembly member 46 and the sun gear member 32 rotateat the same speed as the input shaft 17. The sun gear member 42, thering gear member 34, the planet carrier assembly member 26 and the sungear member 22 do not rotate. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46 and the ring gear/sungear tooth ratio of the planetary gear set 40. The numerical value ofthe eighth forward speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 40.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/SR₁ value is the tooth ratio of the planetary gear set 20;the N_(R2)/SR₂ value is the tooth ratio of the planetary gear set 30;and the N_(R3)/S_(R3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 2.27,while the step ratio between the first reverse speed ratio (Reverse 1)and first forward ratio is −0.47. It should be noted that the single anddouble step forward ratio changes are of the single transition variety.The torque-transmitting mechanism 59 remains engaged through the neutralcondition, thus simplifying the forward/reverse interchange.

FIG. 2 a shows a powertrain 110 having a conventional engine and torqueconverter 12, a planetary transmission 114, and a conventional finaldrive mechanism 16.

The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine and torque converter 12, a planetary geararrangement 118, and an output shaft 19 continuously connected with thefinal drive mechanism 16. The planetary gear arrangement 118 includesthree planetary gear sets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137 rotatablymounted on a carrier member 139 and disposed in meshing relationshipwith both the sun gear member 132 and the ring gear member 134.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152, 154 and 156 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 157, 158 and 159 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member132, and the output shaft 19 is continuously connected with the ringgear member 144. The ring gear member 124 is continuously connected withthe planet carrier assembly member 136 and the ring gear member 142through the interconnecting member 170. The interconnecting member 170may be one component or separate components. The sun gear member 122 iscontinuously connected with the transmission housing 160 through theinterconnecting member 172.

The planet carrier assembly member 126 is selectively connectable withthe ring gear member 134 through the clutch 150. The planet carrierassembly member 126 is selectively connectable with the planet carrierassembly member 146 through the clutch 152. The planet carrier assemblymember 136 is selectively connectable with the sun gear member 132through the clutch 154. The sun gear member 132 is selectivelyconnectable with the planet carrier assembly member 146 through theclutch 156. The ring gear member 134 is selectively connectable with thetransmission housing 160 through the brake 157. The planet carrierassembly member 126 is selectively connectable with the transmissionhousing 160 through the brake 158. The planet carrier assembly member146 is selectively connectable with the transmission housing 160 throughthe brake 159.

The truth tables given in FIGS. 2 b, 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 b,10 b, 11 b, 12 b, 13 b and 14 b show the engagement sequences for thetorque-transmitting mechanisms to provide at least eight forward speedratios and at least one reverse ratio. As shown and described above forthe configurations in FIG. 1 a, those skilled in the art will understandfrom the respective truth tables how the speed ratios are establishedthrough the planetary gear sets identified in the written description.

The truth table of FIG. 2 b describes the engagement sequence of thetorque-transmitting mechanisms utilized to provide three reverse speedratios and eight forward speed ratios. The truth table also provides anexample of the ratios that can be attained with the family members shownin FIG. 2 a utilizing the sample tooth ratios given in FIG. 2 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 120;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set130; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 140. Also shown in FIG. 2 b are the ratio steps between singlestep ratios in the forward direction as well as the third reverse(Reverse 3) to first ratio step. For example, the first to second stepratio is 1.57. It should also be noted that the single step and doublestep forward ratio interchanges are of the single transition variety.

Turning to FIG. 3 a, a powertrain 210 includes the engine and torqueconverter 12, a planetary transmission 214, and a final drive mechanism16. The planetary transmission 214 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 218, and an output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 218 includes three planetary gear sets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247 rotatablymounted on a carrier member 249 and disposed in meshing relationshipwith both the sun gear member 242 and the ring gear member 244.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252, 254, 256 and 257 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 258 and 259 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member232, and the output shaft 19 is continuously connected with the ringgear member 244. The planet carrier assembly member 226 is continuouslyconnected with the ring gear member 234 and the sun gear member 242through the interconnecting member 270. The interconnecting member 270may be one component or separate components. The sun gear member 222 iscontinuously connected with the transmission housing 260 through theinterconnecting member 272.

The ring gear member 224 is selectively connectable with the sun gearmember 232 through the clutch 250. The ring gear member 224 isselectively connectable with the planet carrier assembly member 236through the clutch 252. The ring gear member 234 is selectivelyconnectable with the planet carrier assembly member 246 through theclutch 254. The sun gear member 232 is selectively connectable with theplanet carrier assembly member 246 through the clutch 256. The planetcarrier assembly member 236 is selectively connectable with the planetcarrier assembly member 246 through the clutch 257. The ring gear member224 is selectively connectable with the transmission housing 260 throughthe brake 258. The planet carrier assembly member 246 is selectivelyconnectable with the transmission housing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of two to establish eight forwardspeed ratios (as well as an extra second (2′) and an extra third (3′)forward speed ratio) and two reverse ratios.

The truth table of FIG. 3 b describes the combinations of engagementsutilized for the eight forward speed ratios, the extra second (2′) andextra third (3′) forward speed ratios and the two reverse ratios. Thetruth table also provides an example of speed ratios that are availablewith the family member described above. These examples of speed ratiosare determined utilizing the tooth ratios given in FIG. 3 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 220;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set230; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 240. Also depicted in FIG. 3 b is a chart representing theratio steps between adjacent forward speed ratios and the second reverse(Reverse 2) and first speed ratios. For example, the first to secondratio interchange has a step of 1.87. It can also be readily determinedfrom the truth table of FIG. 3 b that all of the single step and doublestep forward ratio interchanges are of the single transition variety.Additionally, the torque-transmitting mechanism 259 remains engagedthrough the neutral condition, thus simplifying the forward/reverseinterchange.

A powertrain 310, shown in FIG. 4 a, includes the engine and torqueconverter 12, a planetary transmission 314, and the final drivemechanism 16. The planetary transmission 314 includes an input shaft 17continuously connected with the engine and torque converter 12, aplanetary gear arrangement 318, and output shaft 19 continuouslyconnected with the final drive mechanism 16. The planetary geararrangement 318 includes three planetary gear sets 320, 330 and 340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337 rotatablymounted on a carrier member 339 and disposed in meshing relationshipwith both the sun gear member 332 and the ring gear member 334.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354, 356 and 357 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 358 and 359 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member332, and the output shaft 19 is continuously connected with the planetcarrier assembly member 346. The planet carrier assembly member 326 iscontinuously connected with the sun gear member 332 and the sun gearmember 342 through the interconnecting member 370. The interconnectingmember 370 may be one component or separate components. The sun gearmember 322 is continuously connected with the transmission housing 360through the interconnecting member 372.

The ring gear member 324 is selectively connectable with the planetcarrier assembly member 336 through the clutch 350. The planet carrierassembly member 336 is selectively connectable with the planet carrierassembly member 346 through the clutch 352. The planet carrier assemblymember 336 is selectively connectable with the ring gear member 344through the clutch 354. The ring gear member 334 is selectivelyconnectable with the planet carrier assembly member 346 through theclutch 356. The ring gear member 334 is selectively connectable with thering gear member 344 through the clutch 357. The planet carrier assemblymember 336 is selectively connectable with the transmission housing 360through the brake 358. The ring gear member 334 is selectivelyconnectable with the transmission housing 360 through the brake 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. A sample of the numerical valuesfor the ratios is also provided in the truth table of FIG. 4 b. Thesevalues are determined utilizing the ring gear/sun gear tooth ratios alsogiven in FIG. 4 b. The N_(R1)/S_(R1) value is the tooth ratio for theplanetary gear set 320; the N_(R2)/S_(R2) value is the tooth ratio forthe planetary gear set 330; and the N_(R3)/S_(R3) value is the toothratio for the planetary gear set 340. Also given in FIG. 4 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe first reverse (Reverse 1) to first forward speed ratio. For example,the first to second forward speed ratio step is 1.43. It can be readilydetermined from the truth table of FIG. 4 b that each of the forwardsingle step ratio interchanges are of the single transition variety.

A powertrain 410, shown in FIG. 5 a, includes the engine and torqueconverter 12, a planetary transmission 414 and the final drive mechanism16. The planetary transmission 414 includes a planetary gear arrangement418, input shaft 17 and output shaft 19. The planetary gear arrangement418 includes three simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly member 426. The planet carrierassembly member 426 includes a plurality of pinion gears 427 rotatablymounted on a carrier member 429 and disposed in meshing relationshipwith both the sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the sun gear member 432 and the ring gear member 434.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454, 456, 457, 458 and 459. Thetorque-transmitting mechanisms 450, 452, 454, 456 and 457 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 458 and 459 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member432, and the output shaft 19 is continuously connected with the ringgear member 444. The ring gear member 424 is continuously connected withthe ring gear member 434 and the sun gear member 442 through theinterconnecting member 470. The interconnecting member 470 may be onecomponent or separate components. The planet carrier assembly member 426is continuously connected with the transmission housing 460 through theinterconnecting member 472.

The sun gear member 422 is selectively connectable with the planetcarrier assembly member 436 through the clutch 450. The sun gear member422 is selectively connectable with the sun gear member 432 through theclutch 452. The ring gear member 434 is selectively connectable with theplanet carrier assembly member 446 through the clutch 454. The planetcarrier assembly member 436 is selectively connectable with the planetcarrier assembly member 446 through the clutch 456. The sun gear member432 is selectively connectable with the transmission housing 460 throughthe clutch 457. The ring gear member 424 is selectively connectable withthe transmission housing 460 through the brake 458. The planet carrierassembly member 446 is selectively connectable with the transmissionhousing 460 through the brake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide two reverse drive ratiosand eight forward speed ratios (as well as an extra first forward speedratio (1′) and an extra fourth speed ratio (4′)).

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 420; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 440. As can also bedetermined from the truth table of FIG. 5 b, all of the single step anddouble step forward interchanges are of the single transition variety.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the first reverse ratio (Reverse 1) and firstforward ratio. For example, the ratio step between the first and secondforward ratios is 1.99.

A powertrain 510, shown in FIG. 6 a, includes an engine and torqueconverter 12, a planetary gear transmission 514 and the final drivemechanism 16. The planetary transmission 514 includes the input shaft17, a planetary gear arrangement 518 and the output shaft 19. Theplanetary gear arrangement 518 includes three planetary gear sets 520,530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554, 556 and 557 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 558 and 559 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member532, and the output shaft 19 is continuously connected with the planetcarrier assembly member 546. The ring gear member 524 is continuouslyconnected with the planet carrier assembly member 536 and the sun gearmember 542 through the interconnecting member 570. The interconnectingmember 570 may be one component or separate components. The sun gearmember 522 is continuously connected with the transmission housing 560through the interconnecting member 572.

The planet carrier assembly member 526 is selectively connectable withthe sun gear member 532 through the clutch 550. The planet carrierassembly member 526 is selectively connectable with the ring gear member534 through the clutch 552. The planet carrier assembly member 536 isselectively connectable with the planet carrier assembly member 546through the clutch 554. The ring gear member 534 is selectivelyconnectable with the ring gear member 544 through the clutch 556. Thering gear member 534 is selectively connectable with the planet carrierassembly member 546 through the clutch 557. The planet carrier assemblymember 526 is selectively connectable with the transmission housing 560through the brake 558. The ring gear member 544 is selectivelyconnectable with the transmission housing 560 through the brake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide two reversespeed ratios and ten forward speed ratios (as well as an extra sixthforward speed ratio (6′)). Each of the single step and double stepforward interchanges are of the single transition variety. The chart ofFIG. 6 b describes the ratio steps between adjacent forward speed ratiosand the ratio step between the second reverse (Reverse 2) and firstforward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 540.

A powertrain 610, shown in FIG. 7 a, has the engine and torque converter12, a planetary transmission 614 and the final drive mechanism 16. Theplanetary transmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly 626. The planet carrierassembly 626 includes a plurality of pinion gears 627 rotatably mountedon a carrier member 629 and disposed in meshing relationship with boththe sun gear member 622 and the ring gear member 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652, 654, 656 and 657 are rotatingtype torque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 658 and 659 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the ring gear member634, and the output shaft 19 is continuously connected with the ringgear member 644. The ring gear member 624 is continuously connected withthe sun gear member 632 and the sun gear member 642 through theinterconnecting member 670. The interconnecting member 670 may be onecomponent or separate components. The planet carrier assembly member 626is continuously connected with the transmission housing 660 through theinterconnecting member 672.

The sun gear member 622 is selectively connectable with the ring gearmember 634 through the clutch 650. The sun gear member 622 isselectively connectable with the planet carrier assembly member 636through the clutch 652. The sun gear member 632 is selectivelyconnectable with the planet carrier assembly member 646 through theclutch 654. The planet carrier assembly member 636 is selectivelyconnectable with the planet carrier assembly member 646 through theclutch 656. The planet carrier assembly member 636 is selectivelyconnectable with the ring gear member 644 through the clutch 657. Thering gear member 624 is selectively connectable with the transmissionhousing 660 through the brake 658. The planet carrier assembly member646 is selectively connectable with the transmission housing 660 throughthe brake 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide two reversedrive ratios, eight forward speed ratios (as well as an extra fourth(4′), an extra seventh (7′) and an extra eight (8′) forward speedratio), as well as the sequence of these engagements and interchanges.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/S_(R1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/S_(R2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/S_(R3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the second reverse (Reverse 2) to first ratio are also givenin FIG. 7 b. For example, the ratio step between the first and secondforward ratio is 1.50. As can also be determined from the truth table ofFIG. 7 b, each of the single step forward interchanges are of the singletransition variety.

A powertrain 710, shown in FIG. 8 a, has the conventional engine andtorque converter 12, a planetary transmission 714, and the conventionalfinal drive mechanism 16. The engine and torque converter 12 aredrivingly connected with the planetary transmission 714 through theinput shaft 17. The planetary transmission 714 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 714 includes a planetary gear arrangement 718that has a first planetary gear set 720, a second planetary gear set730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly 726. The planet carrierassembly 726 includes a plurality of pinion gears 727 rotatably mountedon a carrier member 729 and disposed in meshing relationship with boththe sun gear member 722 and the ring gear member 724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747 rotatablymounted on a carrier member 749 and disposed in meshing relationshipwith both the sun gear member 742 and the ring gear member 744.

The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754, 756, 757 and 758 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 759 is a stationary-typetorque-transmitting mechanism, commonly termed a brake or reactionclutch.

The input shaft 17 is continuously connected with the planet carrierassembly member 746, and the output shaft 19 is continuously connectedwith the ring gear member 734. The sun gear member 722 is continuouslyconnected with the sun gear member 732 and the sun gear member 742through the interconnecting member 770. The interconnecting member 770may be one component or separate components. The ring gear member 724 iscontinuously connected with the transmission housing 760 through theinterconnecting member 772.

The planet carrier assembly member 726 is selectively connectable withthe planet carrier assembly member 736 through the clutch 750. Theplanet carrier assembly member 726 is selectively connectable with thering gear member 734 through the clutch 752. The planet carrier assemblymember 736 is selectively connectable with the planet carrier assemblymember 746 through the clutch 754. The planet carrier assembly member736 is selectively connectable with the ring gear member 744 through theclutch 756. The planet carrier assembly member 736 is selectivelyconnectable with the planet carrier assembly member 746 through theclutch 757. The ring gear member 734 is selectively connectable with thering gear member 744 through the clutch 758. The planet carrier assemblymember 726 is selectively connectable with the transmission housing 760through the brake 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the eight forward speed ratiosand the reverse speed ratio (as well as the extra second forward speedratio (2′), an extra third forward speed ratio (3′), and an extra fourthforward speed ratio (4′)). Also given in the truth table is a set ofnumerical values that are attainable with the present inventionutilizing the ring gear/sun gear tooth ratios given in FIG. 8 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 720;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set730; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 740. As may be determined from the truth table of FIG. 8 b,each of the single step forward interchanges is of the single transitionvariety. Additionally, the torque-transmitting mechanism 756 remainsengaged through the neutral condition, thus simplifying theforward/reverse interchange.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.43.

A powertrain 810, shown in FIG. 9 a, has the conventional engine andtorque converter 12, a planetary transmission 814, and the final drivemechanism 16. The engine and torque converter 12 are drivingly connectedwith the planetary transmission 814 through the input shaft 17. Theplanetary transmission 814 is drivingly connected with the final drivemechanism 16 through the output shaft 19. The planetary transmission 814includes a planetary gear arrangement 818 that has a first planetarygear set 820, a second planetary gear set 830, and a third planetarygear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly 826. The planet carrierassembly 826 includes a plurality of pinion gears 827 rotatably mountedon a carrier member 829 and disposed in meshing relationship with boththe sun gear member 822 and the ring gear member 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847 rotatablymounted on a carrier member 849 and disposed in meshing relationshipwith both the sun gear member 842 and the ring gear member 844.

The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852, 854, 856, 857 and 858 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 859 is a stationary-typetorque-transmitting mechanism, commonly termed a brake or reactionclutch.

The input shaft 17 is continuously connected with the sun gear member832, and the output shaft 19 is continuously connected with the ringgear member 844. The planet carrier assembly member 826 is continuouslyconnected with the ring gear member 834 and the sun gear member 842through the interconnecting member 870. The interconnecting member 870may be one component or separate components. The sun gear member 822 iscontinuously connected with the transmission housing 860 through theinterconnecting member 872.

The sun gear member 822 is selectively connectable with the sun gearmember 842 through the clutch 850. The ring gear member 824 isselectively connectable with the sun gear member 832 through the clutch852. The ring gear member 824 is selectively connectable with the planetcarrier assembly member 836 through the clutch 854. The planet carrierassembly member 836 is selectively connectable with the sun gear member832 through the clutch 856. The sun gear member 832 is selectivelyconnectable with the planet carrier assembly member 846 through theclutch 857. The planet carrier assembly member 836 is selectivelyconnectable with the planet carrier assembly member 846 through theclutch 858. The planet carrier assembly member 846 is selectivelyconnectable with the transmission housing 860 through the brake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides the three reverse speedratios and eight forward speed ratios shown in the truth table andavailable with the planetary gear arrangement 818. A sample of numericalvalues for the individual ratios is also given in the truth table ofFIG. 9 b. These numerical values have been calculated using the ringgear/sun gear tooth ratios also given by way of example in FIG. 9 b. TheN_(R1)/S_(R1) value is the tooth ratio of the planetary gear set 820;the N_(R2)/S_(R2) value is the tooth ratio of the planetary gear set830; and the N_(R3)/S_(R3) value is the tooth ratio of the planetarygear set 840. It can be readily recognized from the truth table that allof the single step and double step forward interchanges are of thesingle transition variety. FIG. 9 b also describes the ratio stepsbetween adjacent forward ratios and between the third reverse (Reverse3) and first forward ratio. For example, the ratio step between thefirst and second forward ratios is 2.45.

The powertrain 910, shown in FIG. 10 a, includes the conventional engineand torque converter 12, a planetary transmission 914, and theconventional final drive mechanism 16. The engine and torque converter12 are drivingly connected with the planetary transmission 914 throughthe input shaft 17. The planetary transmission 914 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 914 includes a planetary gear arrangement 918that has a first planetary gear set 920, a second planetary gear set930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly 926. The planet carrierassembly 926 includes a plurality of pinion gears 927 that are rotatablymounted on a carrier member 929 and disposed in meshing relationshipwith both the sun gear member 922 and the ring gear member 924.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937 rotatablymounted on a carrier member 939 and disposed in meshing relationshipwith both the sun gear member 932 and the ring gear member 934.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith the sun gear member 942 and the ring gear member 944.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958 and 959. Thetorque-transmitting mechanisms 950, 952, 954, 956, 957 and 958 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanism 959 is a stationary-typetorque-transmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is continuously connected with the sun gear member942, and the output shaft 19 is continuously connected with the ringgear member 934. The ring gear member 924 is continuously connected withthe sun gear member 932 and the ring gear member 944 through theinterconnecting member 970. The interconnecting member 970 may be onecomponent or separate components. The planet carrier assembly member 926is continuously connected with the transmission housing 960 through theinterconnecting member 972.

The planet carrier assembly member 926 is selectively connectable withthe sun gear member 922 through the clutch 950. The sun gear member 922is selectively connectable with the planet carrier assembly member 946through the clutch 952. The sun gear member 922 is selectivelyconnectable with the sun gear member 942 through the clutch 954. The sungear member 932 is selectively connectable with the planet carrierassembly member 936 through the clutch 956. The planet carrier assemblymember 936 is selectively connectable with the planet carrier assemblymember 946 through the clutch 957. The planet carrier assembly member936 is selectively connectable with the sun gear member 942 through theclutch 958. The planet carrier assembly member 936 is selectivelyconnectable with the transmission housing 960 through the brake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide two reverse speed ratios andeight forward speed ratios (as well as an extra first forward speedratio (1′) and an extra fourth forward speed ratio (4′)). The truthtable also provides a set of examples for the ratios for each of thereverse and forward speed ratios. These numerical values have beendetermined utilizing the ring gear/sun gear tooth ratios given in FIG.10 b. The N_(R1)/S_(R1) value is the tooth ratio of the planetary gearset 920; the N_(R2)/S_(R2) value is the tooth ratio of the planetarygear set 930; and the N_(R3)/S_(R3) value is the tooth ratio of theplanetary gear set 940. As can also be determined from the truth tableof FIG. 10 b, each of the single step and double step forwardinterchanges are of the single transition variety.

A powertrain 1010, shown in FIG. 11 a, includes the conventional engineand torque converter 12, a planetary transmission 1014, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1014 through theinput shaft 17. The planetary transmission 1014 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1014 includes a planetary gear arrangement 1018that has a first planetary gear set 1020, a second planetary gear set1030, and a third planetary gear set 1040.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly member 1026. The planetcarrier assembly member 1026 includes a plurality of pinion gears 1027rotatably mounted on a carrier member 1029 and disposed in meshingrelationship with both the sun gear member 1022 and the ring gear member1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of pinion gears 1037rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the sun gear member 1032 and the ring gear member1034.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with both the sun gear member 1042 and the ring gear member1044.

The planetary gear arrangement 1018 also includes seventorque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057, 1058 and1059. The torque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057,1058 and 1059 are rotating type torque-transmitting mechanisms, commonlytermed clutches.

The input shaft 17 is continuously connected with the planet carrierassembly member 1046, and the output shaft 19 is continuously connectedwith the ring gear member 1034. The sun gear member 1022 is continuouslyconnected with the sun gear member 1032 and the sun gear member 1042through the interconnecting member 1070. The interconnecting member 1070may be one component or separate components. The ring gear member 1024is continuously connected with the transmission housing 1060 through theinterconnecting member 1072.

The planet carrier assembly member 1026 is selectively connectable withthe sun gear member 1032 through the clutch 1050. The planet carrierassembly member 1026 is selectively connectable with the planet carrierassembly member 1036 through the clutch 1052. The planet carrierassembly member 1026 is selectively connectable with the ring gearmember 1034 through the clutch 1054. The planet carrier assembly member1026 is selectively connectable with the planet carrier assembly member1046 through the clutch 1056. The planet carrier assembly member 1036 isselectively connectable with the ring gear member 1044 through theclutch 1057. The planet carrier assembly member 1036 is selectivelyconnectable with the planet carrier assembly member 1046 through theclutch 1058. The ring gear member 1034 is selectively connectable withthe ring gear member 1044 through the clutch 1059.

The truth table shown in FIG. 11 b describes the engagement combinationsand the engagement sequence necessary to provide a reverse drive ratioand eight forward speed ratios (as well as an extra second forward speedratio (2′) and an extra third forward speed ratio (3′) and an extrafourth speed ratio (4′)). A sample of the numerical values for theratios is also provided in the truth table of FIG. 11 b. These valuesare determined utilizing the ring gear/sun gear tooth ratios also givenin FIG. 11 b. The N_(R1)/S_(R1) value is the tooth ratio for theplanetary gear set 1020; the N_(R2)/S_(R2) value is the tooth ratio forthe planetary gear set 1030; and the N_(R3)/S_(R3) value is the toothratio for the planetary gear set 1040. As can be determined from FIG. 11b, each of the single step forward interchanges is of the singletransition variety. Also given in FIG. 11 b is a chart describing thestep ratios between the adjacent forward speed ratios and the reverse tofirst forward speed ratio.

A powertrain 1110, shown in FIG. 12 a , includes the convention engineand torque converter 12, a planetary transmission 1114, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1114 through theinput shaft 17. The planetary transmission 1114 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1114 includes a planetary gear arrangement 1118that has a first planetary gear set 1120, a second planetary gear set1130, and a third planetary gear set 1140.

The planetary gear set 1120 includes a sun gear member 1122, a ring gearmember 1124, and a planet carrier assembly member 1126. The planetcarrier assembly member 1126 includes a plurality of pinion gears 1127rotatably mounted on a carrier member 1129 and disposed in meshingrelationship with both the sun gear member 1122 and the ring gear member1124.

The planetary gear set 1130 includes a sun gear member 1132, a ring gearmember 1134 and a planet carrier assembly member 1136. The planetcarrier assembly member 1136 includes a plurality of pinion gears 1137rotatably mounted on a carrier member 1139 and disposed in meshingrelationship with both the sun gear member 1132 and the ring gear member1134.

The planetary gear set 1140 includes a sun gear member 1142, a ring gearmember 1134 and a planet carrier assembly member 1146. The planetcarrier assembly member 1147 includes a plurality of pinion gears 1147rotatably mounted on a carrier member 1149 and disposed in meshingrelationship with both the sun gear member 1142 and the ring gear member1144.

The planetary gear arrangement 1118 also includes seventorque-transmitting mechanisms 1150, 1152, 1154, 1156, 1157, 1158 and1159. The torque-transmitting mechanisms 1150, 1152, 1154, 1156, 1157,1158 and 1159 are rotating type torque-transmitting mechanisms, commonlytermed clutches.

The input shaft 17 is continuously connected with the sun gear member1132, and the output shaft 19 is continuously connected with the planetcarrier assembly member 1146. The ring gear member 1124 is continuouslyconnected with the ring gear member 1134 and the sun gear member 1142through the interconnecting member 1170. The interconnecting member 1170may be one component or separate components. The sun gear member 1122 iscontinuously connected with the transmission housing 1160 through theinterconnecting member 1172.

The planet carrier assembly member 1126 is selectively connectable withthe sun gear member 1122 through the clutch 1150. The planet carrierassembly member 1126 is selectively connectable with the sun gear member1132 through the clutch 1152. The planet carrier assembly member 1126 isselectively connectable with the planet carrier assembly member 1136through the clutch 1154. The ring gear member 1134 is selectivelyconnectable with the planet carrier assembly member 1146 through theclutch 1156. The sun gear member 1132 is selectively connectable withthe ring gear member 1144 through the clutch 1157. The planet carrierassembly member 1136 is selectively connectable with the ring gearmember 1144 through the clutch 1158. The planet carrier assembly member1136 is selectively connectable with the planet carrier assembly member1146 through the clutch 1159.

The truth table shown in FIG. 12 b describes the engagement combinationsand the engagement sequence necessary to provide four reverse speedratios and eight forward speed ratios. The sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 12 b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 12 b. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 1120; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 1130; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 1140. As can be determinedfrom FIG. 12 b, each of the single step interchanges is of the singletransition variety. Also given in FIG. 12 b is a chart describing thestep ratios between the adjacent forward speed ratios and the fourthreverse (Reverse 4) to first forward speed ratio.

A powertrain 1210, shown in FIG. 13 a, includes the conventional engineand torque converter 12, a planetary transmission 1214, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1214 through theinput shaft 17. The planetary transmission 1214 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1214 includes a planetary gear arrangement 1218that has a first planetary gear set 1220, a second planetary gear set1230, and a third planetary gear set 1240.

The planetary gear set 1220 includes a sun gear member 1222, a ring gearmember 1224, and a planet carrier assembly member 1226. The planetcarrier assembly member 1226 includes a plurality of pinion gears 1227rotatably mounted on a carrier member 1229 and disposed in meshingrelationship with both the sun gear member 1222 and the ring gear member1224.

The planetary gear set 1230 includes a sun gear member 1232, a ring gearmember 1234 and a planet carrier assembly member 1236. The planetcarrier assembly member 1236 includes a plurality of pinion gears 1237rotatably mounted on a carrier member 1239 and disposed in meshingrelationship with both the sun gear member 1232 and the ring gear member1234.

The planetary gear set 1240 includes a sun gear member 1242, a ring gearmember 1244 and a planet carrier assembly member 1246. The planetcarrier assembly member 1246 includes a plurality of pinion gears 1247rotatably mounted on a carrier member 1249 and disposed in meshingrelationship with both the sun gear member 1242 and the ring gear member1244.

The planetary gear arrangement 1218 also includes seventorque-transmitting mechanisms 1250, 1252, 1254, 1256, 1257, 1258 and1259. The torque-transmitting mechanisms 1250, 1252, 1254 and 1256 arerotating type torque-transmitting mechanisms, commonly termed clutches.The torque-transmitting mechanisms 1257, 1258 and 1259 are stationarytype torque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is continuously connected with the sun gear member1232, and the output shaft 19 is continuously connected with the ringgear member 1244. The sun gear member 1222 is continuously connectedwith the ring gear member 1234 and the sun gear member 1242 through theinterconnecting member 1270. The interconnecting member 1270 may be onecomponent or separate components. The planet carrier assembly member1226 is continuously connected with the transmission housing 1260through the interconnecting member 1272.

The ring gear member 1224 is selectively connectable with the planetcarrier assembly member 1236 through the clutch 1250. The ring gearmember 1234 is selectively connectable with the planet carrier assemblymember 1246 through the clutch 1252. The planet carrier assembly member1236 is selectively connectable with the planet carrier assembly member1246 through the clutch 1254. The sun gear member 1232 is selectivelyconnectable with the planet carrier assembly member 1246 through theclutch 1256. The ring gear member 1224 is selectively connectable withthe transmission housing 1260 through the brake 1257. The planet carrierassembly member 1236 is selectively connectable with the transmissionhousing 1260 through the brake 1258. The planet carrier assembly member1246 is selectively connectable with the transmission housing 1260through the brake 1259.

The truth table shown in FIG. 13 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. The sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 13 b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 13 b. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 1220; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 1230; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 1240. As can be determinedfrom FIG. 13 b, each of the single step and double step forwardinterchanges is of the single transition variety. Also given in FIG. 13b is a chart describing the step ratios between the adjacent forwardspeed ratios and the second reverse (Reverse 2) to first forward speedratio.

A powertrain 1310, shown in FIG. 14 a, includes the conventional engineand torque converter 12, a planetary transmission 1314, and theconventional final drive mechanism 16. The engine and torque converterare drivingly connected with the planetary transmission 1314 through theinput shaft 17. The planetary transmission 1314 is drivingly connectedwith the final drive mechanism 16 through the output shaft 19. Theplanetary transmission 1314 includes a planetary gear arrangement 1318that has a first planetary gear set 1320, a second planetary gear set1330, and a third planetary gear set 1340.

The planetary gear set 1320 includes a sun gear member 1322, a ring gearmember 1324, and a planet carrier assembly member 1326. The planetcarrier assembly member 1326 includes a plurality of pinion gears 1327rotatably mounted on a carrier member 1329 and disposed in meshingrelationship with the sun gear member 1322. Pinion gears 1328 aredisposed in meshing relationship both the ring gear member 1324 and thepinion gears 1327.

The planetary gear set 1330 includes a sun gear member 1332, a ring gearmember 1334 and a planet carrier assembly member 1336. The planetcarrier assembly member 1336 includes a plurality of pinion gears 1337rotatably mounted on a carrier member 1339 and disposed in meshingrelationship with both the sun gear member 1332 and the ring gear member1334.

The planetary gear set 1340 includes a sun gear member 1342, a ring gearmember 1334 and a planet carrier assembly member 1346. The planetcarrier assembly member 1346 includes a plurality of pinion gears 1347rotatably mounted on a carrier member 1349 and disposed in meshingrelationship with both the sun gear member 1342 and the ring gear member1344.

The planetary gear arrangement 1318 also includes seventorque-transmitting mechanisms 1350, 1352, 1354, 1356, 1357, 1358 and1359. The torque-transmitting mechanisms 1350, 1352, 1354, 1356 and 1357are rotating type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1358 and 1359 arestationary type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is continuously connected with the sun gear member1332, and the output shaft 19 is continuously connected with the ringgear member 1344. The sun gear member 1322 is continuously connectedwith the ring gear member 1334 and the sun gear member 1342 through theinterconnecting member 1370. The interconnecting member 1370 may be onecomponent or separate components. The ring gear member 1324 iscontinuously connected with the transmission housing 1360 through theinterconnecting member 1372.

The planet carrier assembly member 1326 is selectively connectable withthe ring gear member 1334 through the clutch 1350. The planet carrierassembly member 1326 is selectively connectable with the planet carrierassembly member 1336 through the clutch 1352. The planet carrierassembly member 1346 is selectively connectable with the ring gearmember 1344 through the clutch 1354. The planet carrier assembly member1336 is selectively connectable with the planet carrier assembly member1346 through the clutch 1356. The sun gear member 1332 is selectivelyconnectable with the planet carrier assembly member 1346 through theclutch 1357. The planet carrier assembly member 1336 is selectivelyconnectable with the transmission housing 1360 through the brake 1358.The planet carrier assembly member 1346 is selectively connectable withthe transmission housing 1360 through the brake 1359.

The truth table shown in FIG. 14 b describes the engagement combinationsand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. The sample of the numericalvalues for the ratios is also provided in the truth table of FIG. 14 b.These values are determined utilizing the ring gear/sun gear toothratios also given in FIG. 14 b. The N_(R1)/S_(R1) value is the toothratio of the planetary gear set 1320; the N_(R2)/S_(R2) value is thetooth ratio of the planetary gear set 1330; and the N_(R3)/S_(R3) valueis the tooth ratio of the planetary gear set 1340. As can be determinedfrom FIG. 14 b, each of the single step interchanges is of the singletransition variety. Also given in FIG. 14 b is a chart describing thestep ratios between the adjacent forward speed ratios and the reversetwo to first forward speed ratio.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said input shaft being continuouslyinterconnected with a member of said planetary gear sets, and saidoutput shaft being continuously interconnected with another member ofsaid planetary gear sets; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set and with said firstmember of said third planetary gear set; said second member of saidfirst planetary gear set being continuously connected with a stationarymember; a first torque-transmitting mechanism selectivelyinterconnecting a member of said first planetary gear set with a memberof said second or third planetary gear set; a second torque-transmittingmechanism selectively interconnecting a member of said second planetarygear set with a member of said third planetary gear set; a thirdtorque-transmitting mechanism selectively interconnecting a member ofsaid third planetary gear set with a member of said first or secondplanetary gear set; a fourth torque-transmitting mechanism selectivelyinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset; a fifth torque-transmitting mechanism selectively interconnecting amember of said first or third planetary gear set with another member ofsaid first, second or third planetary gear set, or with said stationarymember; a sixth torque-transmitting mechanism selectivelyinterconnecting a member of said second or third planetary gear set withanother member of said first, second or third planetary gear set, orwith said stationary member; and a seventh torque-transmitting mechanismselectively interconnecting a member of said first, second or thirdplanetary gear set with another member of said first, second or thirdplanetary gear set, or with said stationary member; saidtorque-transmitting mechanisms being engaged in combinations of two toestablish at least eight forward speed ratios and at least one reversespeed ratio between said input shaft and said output shaft.
 2. Thetransmission defined in claim 1, wherein said first, second, third,fourth, fifth, sixth and seventh torque-transmitting mechanisms compriseclutches.
 3. The transmission defined in claim 1, wherein said first,second, third, fourth, fifth and sixth torque-transmitting mechanismscomprise clutches, and said seventh torque-transmitting mechanism is abrake.
 4. The transmission defined in claim 1, wherein said first,second, third, fourth and fifth torque-transmitting mechanism compriseclutches and said sixth and seventh torque-transmitting mechanismcomprise brakes.
 5. The transmission defined in claim 1, wherein saidfirst, second, third and fourth torque-transmitting mechanism compriseclutches, and said fifth, sixth and seventh torque-transmittingmechanism comprise brakes.
 6. The transmission defined in claim 1,wherein planet carrier assembly members of each of said planetary gearsets are single-pinion carriers.
 7. The transmission defined in claim 1,wherein at least one planet carrier assembly member of said planetarygear sets is a double-pinion carrier.
 8. A multi-speed transmissioncomprising: an input shaft; an output shaft; a planetary geararrangement having first, second and third planetary gear sets, eachplanetary gear set having first, second and third members; said inputshaft being continuously interconnected with a member of said planetarygear sets, and said output shaft being continuously interconnected withanother member of said planetary gear sets; a first interconnectingmember continuously interconnecting said first member of said firstplanetary gear set with said first member of said second planetary gearset and with said first member of said third planetary gear set; saidsecond member of said first planetary gear set being continuouslyconnected with a stationary member; and seven torque-transmittingmechanisms for selectively interconnecting said members of saidplanetary gear sets with said stationary member or with other members ofsaid planetary gear sets, said seven torque-transmitting mechanismsbeing engaged in combinations of two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between said inputshaft and said output shaft.
 9. The transmission defined in claim 8,wherein a first of said seven torque-transmitting mechanisms is operablefor selectively interconnecting a member of said first planetary gearset with a member of said second or third planetary gear set.
 10. Thetransmission defined in claim 8, wherein a second of said seventorque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said second planetary gear set with a memberof said third planetary gear set.
 11. The transmission defined in claim8, wherein a third of said seven torque-transmitting mechanisms isoperable for selectively interconnecting a member of said thirdplanetary gear set with a member of said first or second planetary gearset.
 12. The transmission defined in claim 8, wherein a fourth of saidseven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset.
 13. The transmission defined in claim 8, wherein a fifth of saidseven torque-transmitting mechanisms is operable for selectivelyinterconnecting a member of said first or third planetary gear set withanother member of said first, second or third planetary gear set or withsaid stationary member.
 14. The transmission defined in claim 8, whereina sixth of said seven torque-transmitting mechanisms is operable forselectively interconnecting a member of said second or third planetarygear set with another member of said first, second or third planetarygear set, or with said stationary member.
 15. The transmission definedin claim 8, wherein a seventh of said seven torque-transmittingmechanisms is operable for selectively interconnecting a member of saidfirst, second or third planetary gear set with another member of saidfirst, second or third planetary gear set, or with said stationarymember.
 16. The transmission defined in claim 8, wherein planet carrierassembly members of each of said planetary gear sets are single-pinioncarriers.
 17. The transmission defined in claim 8, wherein at least oneplanet carrier assembly member of said planetary gear sets is adouble-pinion carrier.